JPH0410600Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) This invention relates to an improvement of a guide mechanism of a fixing device for fixing a toner image formed on copy paper in a copying machine.

(Prior Art) The guide mechanism includes a peeling claw disposed on the paper ejection side of a fixing device including a pair of upper and lower fixing rollers, and a pair of upper and lower guides. When the copy paper that has passed through the fixing device is carried out of the machine through the upper and lower guides and the carry-out roller, if a paper jam occurs between the guides and the paper is deformed, a so-called jam occurs. There is a problem in that the peeling claw is pressed against the fixing roller, and the tip of the peeling claw digs into the outer periphery of the fixing roller, causing damage to the circumferential surface of the fixing roller. For this reason, Utsukai Showa 57-
As shown in Publication No. 164769, a guide is pivoted around the end on the fixing roller side so as to be able to swing up and down, and this guide is supported by an elastic body such as a coil spring. The guide mechanism of the fixing device is such that when a paper jam occurs, the guide swings downward and retreats while elastically deforming the elastic body centered on the end on the fixing roller side due to the deformation of the paper. Proposed. However, in the conventional device described above, the paper is deformed to some extent and a predetermined pressing force is applied, and the guide retracts only when this pressing force becomes greater than the supporting force of the elastic body. A pressing force is also applied to the fixing roller, which may damage the circumferential surface of the fixing roller. Furthermore, if the supporting force of the elastic body is set to be small so that the peeling claw retracts even with a slight pressing force, the weight of the paper may cause the guide to retract, causing a malfunction even if the paper is being conveyed normally. This can easily result in paper being unable to be transported. Furthermore, in the above configuration, the swinging fulcrum of the guide is formed at the end on the fixing roller side, so if copy paper gets caught in the peeling claw and a paper jam occurs near the fixing roller,
Since a pressing force is generated in the vicinity of the swinging fulcrum of the guide, the guide cannot be retracted. In particular, paper jams between the upper and lower guides occur most often near the fixing roller, and when a paper jam occurs near the fixing roller, the greatest pressing force is applied to the peeling claw. In this case, the conventional device in which the guide cannot be retracted has a disadvantage in that it cannot prevent damage to the fixing roller due to the peeling claw biting into the fixing roller.

(Purpose of the invention) This invention was made to eliminate the above-mentioned drawbacks, and is intended to prevent paper jams between the guides on the ejection side of the fixing device in a copying machine.
The peeling claw can be quickly retracted to reliably prevent the peeling claw from digging into the fixing roller, and when the copy paper is being transported normally, the guide is supported in a fixed position and the paper is transferred to the delivery roller. The present invention provides a guide mechanism for a fixing device that can guide the fixing device appropriately.

(Structure of the invention) In other words, this invention has a fixing device equipped with a pair of upper and lower fixing rollers for fixing a toner image formed on a copy sheet, and a peeling claw for peeling off the paper adhered to the fixing roller, on the paper output side of the fixing device. , a guide mechanism of a fixing device including a pair of upper and lower guides for guiding the paper toward an ejection roller; an evacuation means that rotates the guide around a dynamic fulcrum to evacuate the end on the carry-in side; a carry-in detector that detects that paper has been carried into the fixing device; a carry-out detector that detects that the paper has been carried out; and a paper carrying-out detector that detects that the paper has been carried out within a preset transport time from the time when the paper is carried in as detected by the carry-in detector; A paper jam detecting means is provided for outputting a paper jam detection signal to the evacuation means and activating the evacuation means when a paper jam occurs.

(Embodiment) FIG. 1 is a schematic diagram of an electrostatic copying machine that optically scans a document. In the figure, 1 is a contact glass, 2 is an optical system section, and 3 is a photosensitive drum. The optical system unit 2 irradiates light onto a document on a contact glass 1 using an exposure lamp 4 arranged so as to be movable in the horizontal direction, and transmits the reflected light through mirrors 5, 6, 7, a lens 8, and a mirror 9 to be exposed to light. It is configured to expose onto the body drum 3. The above photosensitive drum 3
is rotationally driven by a drum drive device (not shown). Around the photoreceptor drum 3, there is a main charging section 10 that uniformly charges the surface of the photoreceptor drum 3, and a developing section 11 that attracts toner to an electrostatic latent image formed by exposure after charging. , a transfer charging unit 12 that transfers a toner image onto copy paper, and a photosensitive drum 3.
A separation charging section 13 that separates the paper from the paper, a cleaning section 14 that removes residual toner and charges, and a discharge lamp 15 are provided.

In FIG. 1, paper feed mechanisms 16, 16 are disposed on the right side of the photosensitive drum 3, and the copy paper fed from the paper feed mechanisms 16, 16 is transferred to the paper feed guides 17, 17 and the delivery roller 18. , 18 to the transfer area of the photosensitive drum 3, and is then transported to the fixing device 20 via a conveyor 19.

The fixing device 20 includes a pair of upper and lower fixing rollers 21 and 22, as shown in FIG. Usually, a heating element is provided inside the upper fixing roller 21, and a thin coating layer 28 made of silicone rubber, Teflon resin, or the like is formed on the outer periphery. Further, the outer periphery of the lower fixing roller 22 is coated with a pressing elastic material 29 such as silicone rubber. When the copy paper on which the toner image has been formed passes between fixing rollers 21 and 22, it is pressurized and heated so that the toner image is fixed.

A peeling claw 2 is provided on the paper ejection side of the fixing device 20.
3, and a pair of upper and lower guides 26 and 27 for guiding the copy paper toward delivery rollers 24 and 25. The peeling claw 23 is rotatably supported at its base end, and is configured such that its tip abuts against the outer periphery of the upper roller 21 with a predetermined pressing force, and the paper attached to the roller 21 is removed. It is guided by the tip of the peeling claw 23 and peeled off. Note that a plurality of peeling claws 23 are arranged in the axial direction of the pivot shaft.

A rotation fulcrum 30 is provided near the end of the lower guide 27 on the unloading side, that is, in a portion close to the unloading roller 25.
A solenoid type actuator 31 is provided on the lower surface of the guide 27 to forcibly rotate the guide 27 about the rotation fulcrum 30 and retract the unloading end of the guide 27 downward. It is set up. The actuator 31 is connected to the fixing device 2
It operates in response to a paper jam detection signal output from a paper jam detection means having a paper carry-in detector 32 and a paper carry-out detector 33, which are composed of a photo sensor and the like, which are arranged on the carry-in side of the roller 0 and the carry-out side of the carry-out rollers 24 and 25. is configured to do so. That is,
If the carry-out detector 33 does not detect the paper being carried out within a preset conveyance time from the time when the carrying-in of the paper is detected by the carrying-in detector 32, it is determined that a paper jam has occurred. The actuator 31 is actuated upon this determination, and the guide 27 is retracted downward.

In the above configuration, for example, as shown in FIG.
If the paper A is bent or jammed between the upper and lower guides 26 and 27, and the paper A does not reach the ejection detector 33 even after the preset conveyance time has elapsed, the paper A paper jam detection signal is output from the jam detection means to the actuator 31.
As a result, the actuator 31 operates at the initial stage of a paper jam, and the guide 27 rotates around the pivot point 30, causing the end of the guide 27 on the carry-in side to retreat downward as shown by the imaginary line. It is possible to prevent the tip of the peeling claw 23 from digging into the outer periphery of the fixing roller 21. In other words, paper A is in guide 2.
6 and 27, before the paper becomes jammed and becomes extremely deformed, the lower guide 27 is forcibly retracted by the actuator 31 when a signal is output from the paper jam detecting means, so that a large force is applied to the peeling claw 23. No pressure is applied, and it is possible to reliably prevent the peeling claw 23 from digging into the outer periphery of the fixing roller 21. Therefore, it is possible to reliably prevent scratches on the circumferential surface of the fixing roller 21, which would cause poor fixing of the toner image, and damage to the peeling claw 23, which would cause poor peeling of the paper A.

In addition, since the rotation fulcrum 30 of the guide 27 is provided near the end on the unloading side, the end of the paper A is caught on some of the plurality of peeling claws 23, as shown in FIG. Even if paper A is caught in the fixing roller 21 and a paper jam occurs near the ends of the guides 26 and 27 on the carry-in side, the ends of the guides 27 on the carry-in side are forcibly removed by the actuator 31. Paper A is deformed due to being evacuated.
It is possible to reliably prevent the pressing force from acting on the peeling claw 23.

Furthermore, if the copy paper reaches the position where the output detector 33 is provided within the predetermined conveyance time without jamming, the guide 27 is reliably supported in the fixed position by the actuator 31, preventing malfunction. Therefore, it is possible to prevent the occurrence of a situation in which conveyance of paper A becomes impossible.

The specific structure of each part according to this invention can be modified in various ways. For example, an electric motor may be used in place of the solenoid actuator 31, and the guide 27 may be rotated and retracted by the electric motor. You may. Further, a rotation fulcrum is provided near the end of the carry-out side of the upper guide 26, and an evacuation means is provided for rotating the guide 26 around this rotation fulcrum and retracting the end of the carry-in side upward. It may also be a structure. Further, the paper ejection detector 33 may be provided on the inlet side of the ejection rollers 24 and 25. In this case, a paper jam can be detected earlier, and the guide 27 can be more reliably detected before the paper is deformed. , 26 can be evacuated.

(Effects of the invention) As explained above, with this invention, the guide can be forcibly retracted at the initial stage of a paper jam, so the peeling claw is pressed against the fixing roller by the deformed paper, and the tip of the peeling claw is pressed against the fixing roller. This has the advantage that it is possible to reliably prevent the occurrence of a situation in which the fixing roller bites into the outer periphery of the fixing roller, and it is also possible to prevent the circumferential surface of the fixing roller from being damaged and the peeling claw from being damaged. In addition, even if a paper jam occurs near the carry-in side of the guide, where paper jams are most likely to occur and a large pressing force is likely to be applied to the peeling claw, it is possible to forcibly remove the carry-in side end of the guide. Since the fixing roller can be retracted, damage to the circumferential surface of the fixing roller can be reliably and effectively prevented. Moreover, when the paper is being conveyed normally, the guide is reliably supported in a fixed position, and there is an advantage that malfunction does not occur.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the overall configuration of a copying machine;
The figure is an enlarged sectional view of a main part showing an embodiment of this invention, and FIGS. 3 and 4 are sectional views showing the operation of this invention, respectively. 20... Fixing device, 21, 22... Fixing roller, 23... Peeling claw, 24, 25... Carrying out roller, 26, 27... Guide, 30... Rotating fulcrum,
31... actuator (evacuation means), 32...
Carrying-in detector, 33... Carrying-out detector.

Claims (1)

[Scope of utility model registration request] A fixing device equipped with a pair of upper and lower fixing rollers for fixing a toner image formed on copy paper has a paper ejecting side that includes a peeling claw that peels off the paper adhered to the fixing roller, and a peeling claw that guides the paper toward the ejecting roller. A guide mechanism of a fixing device including a pair of upper and lower guides, wherein a rotation fulcrum is provided near an end on an ejection side of at least one of the guides, and the guide is rotated about the rotation fulcrum. an evacuation means for evacuating an end of the paper on the carry-in side; a carry-in detector for detecting that the paper has been carried into the fixing device; and a carry-out detector for detecting that the paper has been carried out from the installation part of the guide. and, if the conveyance detector does not detect the conveyance of paper within a preset transport time from the time when the paper is conveyed as detected by the conveyance detector, the paper jam detection signal is ejected from the paper jam detection signal. A guide mechanism for a fixing device, characterized in that it is provided with a paper jam detection means that outputs an output to the means and activates the paper jam detection means.